Clinical Microbiology Newsletter最新文献

Increasing rates of antibiotic resistance make selecting empiric therapy challenging for the treatment of sepsis and suspected bloodstream infections (BSIs). The time to initiation of effective therapy for BSIs is critical for positive patient outcomes. Recent advances in rapid diagnostics for the detection of BSIs directly from positive blood culture include rapid organism identification and rapid antimicrobial susceptibility testing (AST). Rapid AST methods include genotypic and phenotypic methods or a combination of both and provide important information to aid in the prompt initiation of effective therapy. Genotypic AST methods allow rapid direct detection of a resistance mechanism but may fail to accurately predict a full susceptibility profile, whereas phenotypic AST provides comprehensive results but is not rapid if conventional methods are used. Efforts to decrease the turnaround time of phenotypic AST are an important advancement for the treatment of BSIs. Here, we review currently available and in-development phenotypic methods for AST directly from positive blood culture and their potential benefits for antimicrobial stewardship and patient care.

Monkeypox virus (MPXV) has garnered recent attention as outbreaks are continually reported outside historic regions of endemicity in Africa. Consequently, MPXV is becoming routinely included in the differential diagnosis of rash illnesses, requiring clinicians and laboratorians alike to quickly adapt to a new public health emergency. This review discusses the epidemiology, clinical presentation, and laboratory testing of MPXV in the context of recent outbreaks.

The most common dimorphic fungi isolated from clinical specimens in North America are Coccidioides immitis, Coccidioides posadasii, Blastomyces dermatitidis species complex, and Histoplasma capsulatum. These organisms are typically definitively identified at reference or public health laboratories, as they are risk group 3 (RG3) pathogens requiring additional biosafety considerations compared to risk group 2 (RG2) pathogens. Reference and public health laboratories have been using organism-specific DNA probes since the early 1990s as the primary method of confirming the identification of morphologically suspect dimorphic fungi growing in culture. At the end of November 2021, manufacturing of these probes was discontinued, leaving clinical laboratories responsible for dimorphic fungus identification with the task of validating and implementing a new identification method for these pathogens. Here, we discuss alternatives to DNA probes for identification of Coccidioides spp., B. dermatitidis species complex, and H. capsulatum growing in culture, including the strengths and limitations of each method.

Diagnostic stewardship aims to improve diagnostic test utilization through evidence-based practices to improve care, quality, safety, and costs. Diagnostic stewardship is a collaborative effort that brings together multidisciplinary groups that have a common interest in promoting and ensuring best testing practices. For infectious disease testing, clinical microbiology laboratories are perhaps best positioned within their health care systems to lead these efforts, as they are not only diagnostic experts, but also directly oversee many of the tools and choices available to improve test performance and utilization. While some interventions may not fall under the direct purview of clinical microbiology laboratories, their expertise is nevertheless essential to inform these efforts, as well. Multiple stewardship strategies have been evaluated, providing laboratories with several opportunities to implement evidence-based practice changes to improve quality and outcomes. Further research is needed to continue advancing practice for well-established and emerging tests alike.

Gram-negative non-fermentative bacilli, such as Achromobacter spp., can be opportunistic pathogens in nosocomial settings. Widely found in nature, Achromobacter spp. cause a broad spectrum of diseases and are best known as emerging opportunistic pathogens in the lungs of cystic fibrosis patients. Importantly, Achromobacter infections represent a diagnostic and clinical challenge. First, clinical laboratories cannot routinely identify Achromobacter isolates reliably to the species level outside of creating and curating a custom mass spectrometry database or using Achromobacter-specific genotypic molecular methods. Additionally, Achromobacter spp. infections are often difficult to treat owing to numerous intrinsic, and to a lesser extent acquired, antimicrobial resistance mechanisms. Treatment decisions are further complicated by discordance between CLSI and EUCAST breakpoints for antimicrobial susceptibility testing of Achromobacter isolates, and collaboration to harmonize these is necessary. Further studies are also needed to define the clinical spectrum of disease and pathogenic potential of many Achromobacter species.

Strongyloidiasis, typically caused by Strongyloides stercoralis, is a neglected tropical disease that affects 30 to 100 million people worldwide. Despite the commonly asymptomatic nature of the infection, S. stercoralis infection of immunocompromised individuals can be lethal. Infected but asymptomatic immunocompetent individuals can develop hyperinfection or disseminated infection if they experience any significant change in their immune status, and recently, cases have been described following the use of corticosteroids to treat COVID-19-related pneumonia. Definitive diagnosis is established via stool examination for rhabditiform larvae; however, contemporary methods, including serologic and molecular testing, are increasingly used as adjunct tests. Importantly, exposed individuals and those expected to become immunosuppressed should be screened and pre-emptively treated before starting immunosuppressive agents to avoid cases of dissemination and hyperinfection.